Mercury

“The effect of exposure to inorganic mercury on the pregnant woman and her foetus has received little attention. Transport of elemental inorganic mercury into foetal tissues has been reported, and prior studies indicate a higher incidence of adverse pregnancy outcome. The effects of occupational exposure to inorganic mercury on pregnancy were investigated among 46 exposed women workers: controls were 19 women working in non-production areas of the same factory. There were 104 recorded total pregnancies during the period 1948-77. The study revealed a higher frequency of adverse reproductive outcomes, especially congenital anomalies, among the women exposed to inorganic mercury levels at or substantially lower than 0.6 mg/m3; no significant differences in the stillbirth or miscarriage rates were noted between the two groups of women. The overall foetal death rate in this study was similar to New York state (USA) and national levels for the same period.”

“20 000 subjects were enrolled in a large-scale field study to determine the concentration of total mercury in saliva. A statistical relationship was found between the mercury concentration in the pre-chewing saliva and chewing saliva, and the number of amalgam fillings. The mean number of amalgam fillings was 9 and the median mercury concentration was 11.6 µg/1 in the pre-chewing saliva and 29.3 µg/1 in the chewing saliva, which is considerably higher than reported in most previous publications. Extrapolation to the uptake of total mercury per week has shown that the provisional tolerable weekly intake (PTWI) value of the WHO is exceeded in at least 30% of the subjects.”

Seven female subjects diagnosed with mulitple sclerosis were tested for hearing at threshhold frequencies of 250, 500, 1000, 4000 and 8000 Hz. The subjects then had their silver dental fillings (amalgams) removed. Between six and eight months after amalgam removal, testing for hearing was repeated. Six of the seven subjects showed improvement in hearing of the right ear and five of the seven showed improvement in the left ear. Four of the six frequencies tested in the right ear improved significantly and three of six improved significantly in the left ear. The total frequencies were averaged before amalgam removal and compared to after amalgam removal. Hearing improved an average of 8 db (p=0.02).

RESULTS:
After removal of all amalgam restorations, only the non-rubber dam group showed significant increases in the mercury levels found in plasma (p = 0.012) and urine (p = 0.037). However, one year later, the mercury levels in plasma and urine had sunk significantly below the pre-removal levels for both groups. When the changes in the mercury levels found were compared between the groups, the non-rubber dam group showed a significantly higher increase of mercury in plasma than the rubber dam group the day after removal (p = 0.0010). Compared to the pre-removal mercury levels in plasma and urine, the levels found 1 y after removal of all amalgam restorations were on average 52 +/- 23% (range 4-89%) lower in plasma and 76 +/- 21% (range 20-94%) lower in urine.

SIGNIFICANCE:
The study showed that dental amalgam had a statistically significant impact on the mercury levels found in plasma and urine in the patients tested, and that the use of a rubber dam during removal of all amalgam restorations significantly reduced the peak of mercury in plasma following removal.

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In this web-document by Ulf Bengtsson you will learn more about the background, and you will find a description of an experiment performed in 1986 with thorough pictorial documentation, including a QuickTime movie showing how the mercury droplets form on the surface of non-gamma-two amalgams. All fully referenced. When you look at these droplets you actually look at something the establishment of the dental and medical communities don’t want to see, and also have gone into considerable efforts not to be made seen by others. What you see is a real phenomenon.

Clinical signs, somatic symptoms reported by patients, and mercury excretion in urine were studied for 348 patients selected by odontologists or internists as amalgam-free referents, or as subjects with unexplained clinical findings or who were self-selected due to their fear of mercury intoxication from their amalgam fillings. Sixty patients were excluded because other explanations could be given for their complaints. The age distribution was bimodal, with peaks between 30 and 35 years and between 45 and 50 years. Mercury was determined in a morning urine sample and 30 minutes after the injection of 300 mg of 2,3 dimercapto-1-propane sulfonic acid (DMPS), a mercury-chelating agent. The patients were followed for 1-3 years. Among the patients there were 26 who had had their amalgam fillings removed and who, at the time of the follow-up, were subjectively cured. When the patients were classified according to the excretion of mercury after the DMPS challenge, those who belonged to the upper quartile had an odds ratio of 7.2 (95% confidence interval 3.1-15.2) for becoming cured after amalgam removal. The symptoms of the cured patients had been predominantly mental. No consistent clinical picture could, however, be found among the other patients, as various types of mental and physical distress were reported.

“Brain metallothionein (MT) protein and mRNA levels were determined in the fetal rat following in utero (gestational days 7-21) exposure to elemental mercury vapor (Hg0; 300 microg Hg/m3; 4 h/day). Total RNA was probed on Northern blots with [alpha-32P]dCTP-labeled synthetic cDNA probes specific for rat MT isoform mRNAs. The probes for MT-I and MT-II mRNA hybridized to a single band of approximately 550 and 450 nucleotides, respectively. Expression of whole brain MT-I mRNA in full-term fetal rats (day 21) was significantly increased (P < 0.03) by in utero exposure to Hg0 compared to nonexposed controls. This corresponded to a 14-fold increase (P < 0.001) in fetal brain Hg concentration after in utero Hg0 exposure. In addition, astrocytes from both control and in utero Hg0-exposed fetuses were isolated, and neonatal primary astrocyte cultures were established and maintained in vitro for up to 3 weeks without additional experimental intervention. Astrocyte monolayers derived from in utero Hg0-exposed fetuses consistently expressed increased abundance of MT-I mRNA transcripts after 1, 2, and 3 weeks in culture (P < 0.03, P < 0.01, and P < 0.03, respectively) compared with controls. The abundance of astrocyte MT-II mRNA was unchanged at 1 and 2 weeks in culture, but was significantly increased at 3 weeks in cultures derived from brains of Hg0-exposed fetuses (P < 0.04). Consistent with the increase in MT mRNA, an increase in astrocytic levels of MT proteins was noted by Western blot analysis and MT-immunoreactivity. These studies suggest that in utero exposure to Hg0 induces brain MT gene expression, and that MT mRNAs and their respective proteins are useful quantitative biochemical markers of intrauterine exposure to Hg0, a potentially cytotoxic challenge to astrocytes in the developing brain. It is concluded that induction of MT by fetal/neonatal astrocytes represents an attempt by these glial cells to protect against Hg cytotoxicity in maintaining cerebral homeostasis.”

This review examines the question of whether adverse health effects are attributable to amalgam-derived mercury. The issue of absorbed dose of mercury from amalgam is addressed first. The use of intra-oral Hg vapor measurements to estimate daily uptake must take into account the differences between the collection volume and flow rate of the measuring instrument and the inspiratory volume and flow rate of air through the mouth during inhalation of a single breath. Failure to account for these differences will result in substantial overestimation of the absorbed dose. Other factors that must be considered when making estimates of Hg uptake from amalgam include the accurate measurement of baseline (unstimulated) mercury release rates and the greater stimulation of Hg release afforded by chewing gum relative to ordinary food. The measured levels of amalgam-derived mercury in brain, blood, and urine are shown to be consistent with low absorbed doses (1-3 micrograms/day). Published relationships between the number of amalgam surfaces and urine levels are used to estimate the number of amalgam surfaces that would be required to produce the 30 micrograms/g creatinine urine mercury level stated by WHO to be associated with the most subtle, pre-clinical effects in the most sensitive individuals. From 450 to 530 amalgam surfaces would be required to produce the 30 micrograms/g creatinine urine mercury level for people without any excessive gum-chewing habits. The potential for adverse health effects and for improvement in health following amalgam removal is also addressed. Finally, the issue of whether any material can ever be completely exonerated of claims of producing adverse health effects is considered.